Outer Longitudinal Muscle Research Articles

Muscle System of <i>Aspidogaster limacoides</i> (Trematoda, Aspidogastridae )

The article describes the musculature of the body, the pharynx and the ventral disc of Aspidogaster limacoides. The body wall contains three muscle layers: circular, longitudinal and diagonal. Numerous chordal muscles oriented both transversely and longitudinally, along with body wall and radial musculature, precondition the oral funnel mobility. Apart from radial, the pharynx musculature includes outer longitudinal, inner circular and outer circular muscles, the latter forming the anterior sphincter. The ventral disc being alveolar in its structure, the diversity of its musculature is restricted: the septa contain no chordal muscles or sphincters. The architectonics of parenchymal musculature has three main features resulting from large disc size, i.e. the presence of two muscle septa in the parenchima, dorso-ventral musculature being located latero-ventrally from muscle septa and a considerable development of viscero-motor muscles.

Remodeling of Uterine Tissues During Gestation of Potamotrygon wallacei (Elasmobranchii), a Neotropical Freshwater Stingray Endemic to the Negro River, Central Amazonia.

Neotropical freshwater stingrays of the subfamily Potamotrygoninae exhibit aplacental viviparity with uterine trophonemata. In this reproductive mode, females nourish and provide oxygenation to the embryo via the mucosa of the uterine wall. The aim of this study was to describe and histologically quantify the tissue components of the gravid uterus in an Amazonian freshwater stingray. Adult females of Potamotrygon wallacei were studied in different reproductive periods: resting stage, pregnant, and postpartum. During reproductive rest, the left ovary has numerous follicles compared to the right side. Therefore, uterine fertility is usually higher on the left side. The presence of an embryo in the right uterus suggests that the right ovary is also functional, although this only occurs in larger females. In females at reproductive rest, the wall of the uterus is formed by a mucosal layer (without the trophonemata) that contributes 16.7% to the thickness, while the myometrium accounts for 83.3% of the thickness. The mass-specific volume of the mucosal layer, inner circular, and outer longitudinal smooth muscle sheets tend to increase in the gravid uterus, indicating hypertrophy and hyperplasia of these components. During pregnancy, the trophonemata undergo marked tissue remodeling. Epithelial cells are organized into glandular acini and have apical secretory vesicles; furthermore, peripheral blood vessels proliferate and become dilated. These characteristics demonstrate that the gravid uterus of P. wallacei presents intense uterolactation activity and provides oxygenation to the fetus. Tissue remodeling occurs only in the uterus with the presence of an embryo. During postpartum, females have low body condition factor indicating a high reproductive cost. This study contributes to the knowledge of the reproductive biology of this species and will help us understand the impacts of climate change on the breeding areas of potamotrygonids.

Distribution and ultrastructural characteristics of enteric glial cell in the chicken cecum

Enteric glial cell (EGC) is involved in neuroimmune regulation within the enteric nervous system (ENS); however, limited information exists on the distribution and ultrastructure of EGC in the poultry gut. We aim to investigate the morphological features and distribution of EGC in the chicken cecum. Here, we investigated the distribution and ultrastructural features of chicken cecum EGC using immunohistochemistry (IHC) and transmission electron microscopy (TEM). IHC showed that EGC was widely distributed throughout the chicken cecum. In the mucosal layer, EGC was morphologically irregular, with occasionally interconnecting protrusions that outlined signal-negative neurons. The morphology of EGC in the submucosal layer was also irregular. In the inner circular muscle layer and between the inner circular and outer longitudinal muscle layers, EGC aligned parallel to the circular muscle cells. A small number of EGC with an irregular morphology were found in the outer longitudinal muscle layer. In addition, in the submucosal and myenteric plexus, EGC were aggregated, and the protrusions of the immunoreactive cells interconnected to outline the bodies of nonreactive neurons. TEM-guided ultrastructural characterization confirmed the IHC findings that EGC were morphologically irregular and revealed they developed either a star, bipolar, or fibrous shape. The nucleus was also irregular, with electron-dense heterochromatin distributed in the center of the nucleus or on the nuclear membrane. The cytoplasm contained many glial filaments and vesicle-containing protrusions from neuronal cells; organelles were rare. EGC was in close contact with other cells in their vicinity. These findings suggest that EGC is well-situated to exert influence on intestinal motility and immune functions through mechanical contraction and chemical secretion.

Maturation and development of fetal pig intestinal tissue in immunodeficient mice.

This study aimed to compare the degree of maturation and development of fetal pig segmental intestinal tissue with that of spheroids created by in-vitro reaggregation of dissociated fetal intestinal cells after transplantation into immunodeficient mice. Fetal pig small intestines were transplanted as segmental grafts into the omentum and subrenal capsules of immunodeficient mice or enzymatically treated to generate single cells. Spheroids made by in-vitro reaggregation of these cells were transplanted into the subrenal capsules of immunodeficient mice. The segmental grafts and spheroids were harvested four and eight weeks after transplantation, and the structural maturity and in-vivo development of these specimens were histologically evaluated. The spheroids were engrafted and supplied blood vessels from the host mice, but an intestinal layered structure was not clearly observed, and there was almost no change in size. On the other hand, the segmental grafts formed deep crypts in the mucus membrane, the inner circular layer, and outer longitudinal muscles. The crypts of the transplanted grafts harvested at eight weeks were much deeper, and the smooth muscle layer and the enteric nervous system were more mature than those of grafts harvested at the fourth week, although the intestinal peristaltic wave was not observed. Spheroids created from fetal small intestinal cells could not form layered structures or mature sufficiently. Conversely, segmental tissues structurally matured and developed after in-vivo transplantation and are therefore potential grafts for transplantation.

Epigenomic analysis of the myometrium during late implantation revealed regulatory elements in genes related to the cellular zinc homeostasis pathway in pigs

The myometrium, composed of the inner circular muscle (CM) and outer longitudinal muscle (LM), is crucial in establishing and maintaining early pregnancy. However, the molecular mechanisms involved are not well understood. In this study, we identified the transcriptomic features of the CM and LM collected from the mesometrial (M) and anti-mesometrial (AM) sides of the pig uterus on day 18 of pregnancy during the placentation initiation phase. Some genes in the cellular zinc ion level regulatory pathways (MT-1A, MT-1D, MT-2B, SLC30A2, and SLC39A2) were spatially and highly enriched in uterine CM at the mesometrial side. In addition, the histone modification profiles of H3K27ac and H3K4me3 in uterine CM and LM collected from the mesometrial side were characterized. Genomic regions associated with the expression of genes regulating the cellular zinc ion level were detected. Moreover, six highly linked variants in the H3K27ac-enriched region of the pig SLC30A2 gene were identified and found to be significantly associated with the total number born at the second parity (P < 0.05). In conclusion, the genes in the pathways of cellular zinc homeostasis and their regulatory elements identified have implications for pig reproduction trait improvement and warrant further investigations.

PATHOMORPHOLOGICAL CHANGES IN THE ORGANS OF CATS CAUSED BY ALIMENTARY LYMPHOMA. CLINICAL CASES

The article presents the results of clinical, ultrasonographic, pathomorphological and immunohistochemical studies of two random cases of alimentary lymphoma in 9- and 12-year-old domestic cats. Clinical signs of the disease were similar and characterized by anorexia, cachexia, vomiting and diarrhea that appeared in different periods of the disease. The mucous membranes of the oral cavity and eyes were icteric, the abdomen was visually enlarged, palpation revealed nodular thickenings in the abdominal cavity. During the ultrasound diagnostics, diffuse multiple non-encapsulated anechoic formations with uneven edges and growth of tumorous tissue into the intestinal wall were visualized. In another cat, there was an encapsulated formation of a hypoechoic fine-grained structure with well-defined vascularization.&#x0D; From the moment of the preliminary diagnosis until the very death, the cats were kept in the clinic under supervision. After the death, an autopsy was performed with the selection of material for histopathological examination. Organs’ fragments were fixed in 10% aqueous solution of neutral formalin and Carnois fluid. Histological preparations were made according to the generally accepted methods. Immunophenotyping of lymphoma type was performed using CD3 (T-cell) and CD79a (B-cell) markers. During the pathological autopsy, an increase in mesenteric lymph nodes, their compaction, and focal thickening of the small intestine wall were revealed. The histological examination showed that jejunum was the most infiltrated intestinal segment, in which massive, diffusely placed monomorphic lymphoblastic cells were localized in the mucous membrane lamina, submucosa and muscle layers. The submucosal layer vessels were sharply dilated, filled with erythrocytes; the muscles of the inner circular layer were swollen. The outer (longitudinal) muscle layer of the jejunum thickened significantly and was intensively infiltrated by lymphoblastic cells.&#x0D; Typical diffuse lymphoblastic proliferations were also detected in the cortical substance of lymph nodes and lymphoid nodules. Stasis and significant expansion of the marginal sinus vessels were visualized too. In addition, moderate mononuclear lymphoblastic infiltrates were detected in the pancreas parenchyma with their perivascular location. Immunohistochemically, a significant positive expression of CD3 cells was detected both in the jejunum mucous membrane and the marginal sinus area, around the germinal centers of the lymph nodes, which indicated a T-cell type of lymphoma.

A study on the congruence and proximity of the sling and clasp fibres at the cardio-esophageal junction of the stomach.

The cardio-oesophageal sphincter that is located in close longitudinal proximity to the origin of the lesser curvature of the stomach has a unique pattern of external muscle fibres whose inner oblique layer would normally form an elongated sling and the middle partially circular layer would form a projecting clasp into the already existing muscular sling of the former congruently, which would result in the formation of an anatomical sphincter in that area that would normally be devoid of the external longitudinal muscle layer coat. Certain authors have disagreed with the notion of this standard literature and have proposed that the clasp and sling fibres need not necessarily be congruent and may even remain independent of each other with partial contributions from the longitudinal muscle layers as well that may arise tangentially in different populations, which may in turn contribute to reflux oesophagitis in that population. Hence, the clasp and sling fibre muscular patterns were observed in six formalin-embalmed cadavers at the department of anatomy in a tertiary care institute as part of routine dissections in series, and the findings were then reported. At the junction of the lesser curvature of the stomach with the oesophagus, all six cadavers showed a longitudinal sling pattern as opposed to the conventional oblique sling. The circular muscle layer was found to be merged with the outer longitudinal muscle layer to form the sling that pulled away from the clasp, resulting in a loss of congruency for the same. The clasp fibres, however, were found to be contributed by the inner oblique muscle layer. The conventional perpendicular or tangential merging of the clasp with the sling was not observed; instead, an obtuse, blunt angular merging of the clasp with the sling was observed. The deviation of the sling from the clasp could indicate a lack of a proper fit between them at the cardio-oesophageal sphincter. The lack of robustness in the attachment of the clasp to the sling may possibly contribute to the diminished taut pull of the clasp in this subset of the population. These would be significant determinants for a predisposition to reflux oesophagitis and Barrett's oesophagus.

Comparison of the Development and Involution Periods of Bursa of Fabricius with Histological and Histochemical Methods

The aim of this study is to histologically and histochemically determine the developmental and involutional stages of bursa of Fabricius of henna partridge (Alectoris chukar). In the study, bursa of Fabricius of 12 3-month-old (6 males, 6 females), 12 6-month-old (6 males, 6 females) henna partridges purchased from a private farm were used. It was observed that bursa of Fabricius was surrounded by a connective tissue capsule and consisted of tunica serosa, tunica muscularis, and tunica mucosa layers from the outside to the inside. It was seen that the tunica muscularis consisted of outer longitudinal and inner circular smooth muscle fibers. It was observed that the tunica mucosa made plicae towards the lumen of the organ and consisted of 10-15 plicae. It was seen that lamina epithelialis and lymph follicles were present in each plica. It was determined that the lamina epithelialis consisted of two parts called FAE (Follicle-Associated Epithelium) and IFE (İnter Follicular Epithelium). It was noted that the lymph follicles contained cortex and medulla sections and were separated locally by capillaries together with cortical medullary boundry cells. In the Methyl Green-pyronin staining method, plasma cells were found in the bursa of Fabricius of the henna partridge, in the connective tissue surrounding the organ, around the blood vessels and inside the follicles. In AB pH=2.5 staining, AB-positive reaction was seen only in the apical part of the epithelial cells forming FAE and IFE in the pre- and post-involution period. In PAS staining, PAS-positive reaction was observed only in the apical part of the epithelial cells forming FAE and IFE in the pre- and post-involution period. In PAS/AB pH=2.5 combined staining method, AB-positive reaction was observed only in the apical part of epithelial cells in the pre- and post-involution period. As a result of this study, it was found that bursa of Fabricius of the henna partridge did not undergo any histochemical changes despite its histologically large differences after involution.

Integrating Transcriptomic and ChIP-Seq Reveals Important Regulatory Regions Modulating Gene Expression in Myometrium during Implantation in Pigs

The myometrium is the outer layer of the uterus. Its contraction and steroidogenic activities are required for embryo implantation. However, the molecular mechanisms underlying its functions remain unknown in pigs. The myometrium includes the inner circular muscle (CM) and the outer longitudinal muscle (LM) layers. In this study, we collected the CM and LM samples from the mesometrial side (named M) of the uterus on days 12 (pre-implantation stage) and 15 (implantation stage) of pregnancy and day 15 of the estrous cycle. The transcriptomic results revealed distinct differences between the uterine CM and LM layers in early pregnancy: the genes expressed in the LM layer were mainly related to contraction pathways, whereas the transcriptional signatures in the CM layer on day 15 of pregnancy were primarily involved in the immune response processes. Subsequent comparisons in the CM layer between pregnant and cyclic gilts show that the transcriptional signatures of the CM layer are implantation-dependent. Next, we investigated the genome-wide profiling of histone H3 lysine 27 acetylation (H3K27ac) and histone H3 lysine 4 trimethylation (H3K4me3) in pig uterine CM and LM layers. The genomic regions that had transcriptional activity and were associated with the expression of genes in the two layers were characterized. Taken together, the regulatory regions identified in the study may contribute to modulating the gene expression in pig uterine CM and LM layers during implantation.

Dog and human bladders have different neurogenic and nicotinic responses in inner versus outer detrusor muscle layers.

The aim of this study was to investigate layer and species variations in detrusor muscle strip responses to myogenic, neurogenic, and nicotinic, and muscarinic receptor stimulations. Strips from bladders of 9 dogs and 6 human organ transplant donors were dissected from inner and outer longitudinal muscle layers, at least 1 cm above urethral orifices. Strips were mounted in muscle baths and maximal responses to neurogenic stimulation using electrical field stimulation (EFS) and myogenic stimulation using potassium chloride (KCl, 120 mM) determined. After washing and re-equilibration was completed, responses to nicotinic receptor agonist epibatidine (10 μM) were determined followed by responses to EFS and muscarinic receptor agonist bethanechol (30 μM) in continued presence of epibatidine. Thereafter, strips and full-thickness bladder sections from four additional dogs and three human donors were examined for axonal density and intramural ganglia. In dog bladders, contractions to KCl, epibatidine, and bethanechol were 1.5- to 2-fold higher in the inner longitudinal muscle layer, whereas contractions to EFS were 1.5-fold higher in the outer (both pre- and post-epibatidine). Human bladders showed 1.2-fold greater contractions to epibatidine in the inner layer and to EFS in the outer, yet no layer differences to KCl or bethanechol were noted. In both species, axonal density was 2- to 2.5-fold greater in the outer layer. Dogs had more intramural ganglia in the adventitia/serosa layer, compared with more internal layers and to humans. These findings indicate several layer-dependent differences in receptor expression or distribution, and neurogenic responses in dog and human detrusor muscles, and myogenic/muscarinic differences between dog versus humans.

Histological and histochemical study of large intestine in Camel (Camelus Dromedarius)

Current study was performed to describe the Histohistological and histochemical structures of the large intestine in Iraqi one humped camel (Camelus Dromedarius). Five healthy male camels Approximately 3 to 4 years old were chosen and their specimens from cecum, colon and rectum. The specimens were directly transferred after the animal’s slaughtering to the histology lab at College of Veterinary Medicine for subsequent histological techniques. Tissue specimensfrom various parts of the large intestine (cecum, colon and rectum) were collected and fixed with 10% neutral buffered formalin then subjected to routine tissue processing. Sections of 6 micrometers thickness were prepared and stained with hematoxylin and eosin (H&amp;E) for general histology and Periodic Acid Schiff combine with Alcian blue (AB–PAS), Masson's trichrome as well as Verhoeff stains for histochemical description. Microscopic findings revealed four tunicae constructing the wall of cecum, colon and rectum mucosa, that were from the inner most mucosa, submucosa, muscularis and the outer most either serosa or adventitia. The tunica mucosa characterized by simple columnar epithelium rested on basement membrane and the presence of muscularis mucosa which separated mucosa from the underneath submucosa. Crypts of Lieberkühn and goblet cells were abundant in the colonic epithelium. The submucosa was made up of irregular connective tissue rich with adipose tissue and was supplied well with many blood vessels. Tunica muscularis in all over the three parts of large intestine was made up of inner circular smooth muscle fibers and outer longitudinal smooth muscle fibers. The tunica serosa, and in parts replaced by adventitia, was made up of loose connective tissues.

Histomorphogenic changes during uterine development of the Nigerian indigenous breed of dog: A post-natal study

Demand for dog is on an increase because they are used as watchdog, hunting and its breeding serves as a source of income to both rural and urban dwellers. As demand is increases, breeders often mate dogs at premature age thereby causing several complications from conception to birth. This study was aimed at considering the post-natal development of the uterus from histomorphological aspects and to correlate features to attainment of puberty. Hysterectomy was carried out to secure the uterus from Day 2, Week 4, Week 8, Week 12 and Week 20. This developmental study attempted highlighting some silent microanatomical parameters, including the circular muscle, longitudinal muscle, myometrial glands, blood vessels and epithelial features of the uterus in the Nigerian indigenous bitch. The inner circular muscle and the germinal epithelium were the first microstructures to be observed on day 2 and week 4 of postnatal development respectively. Within these range of development, little or no histological variations occurred. Simple columnar epithelium and longitudinal smooth muscle were seen on the twelfth week. The inner circular muscle and outer longitudinal muscles made up the fundamental component of the smooth muscle. The significant of this study is to indicate histological changes that takes place within the uterus and this finding show some corresponding relationship that exist between age and uterine development, an indicator for determining puberty.

Histological structure and evaluation of cellular layers of Large intestine in Guinea pig (Cavia porcellus)

The Aim of this study is to determine the histological structure in the wall layers of large intestine of guinea pig. The cecum and colon was characterized by a delicate lining that is moisturized by mucus and also by a gel that is a by-product of bacterial fermentation. This study was performed on the cecum and ascending and descending colon in five health animals. The cecum and colon wall was composed of four tunicae (mucosa, submucosa, muscularis and serosa, the tunica mucosa consist of epithelium, lamina propria and muscularis mucosa. The colon lumen lined by simple columnar epithelium with prominent goblet cells. The epithelial surface of the colon is covered by the openings of tubular intestinal glands which penetrate deep into the thick mucosa. The glands consist of absorptive cells that absorb water and salt, goblet cells were secrete the mucus, and scattered Paneth cells. Crypts of Lie beckon (intestinal glands) are a simple tubular glands is observe in most mammals, which extending from the muscularis mucosa through the thickness of the lamina propria and they open into the intestinal lumen. Muscularis mucosa, consisted of very thin two layers of inner circular and outer longitudinal smooth muscles, the greater thickness of the muscularis mucosa was in the adult type and the submucosa was consists of dense a irregular connective tissue. The muscular layer is consists of internal circular and external longitudinal layers of smooth muscles, which mean their thickness is decreased toward the last parts. Thus, the serous coat is a thin layer of loose connective tissue, the thickness was decreases toward the last parts.

Concordance and survival implications of preoperative subclassification of T3 rectal cancers by depth of mesorectal invasion using a 5-mm cut-off point with endorectal ultrasound and magnetic resonance imaging.

Validated rectal cancer staging groups T3 tumours in a single stage and depth of mesorectal invasion subclassification is not standard practice. Our aim is to report concordance between magnetic resonance imaging (MRI) and endorectal ultrasound (ERUS) for preoperative staging of T3 rectal tumours using a 5-mm cut-off point and possible survival implications. Prospective cohort study including patients staged preoperatively as cT3 by ERUS or magnetic resonance imaging. The maximum depth of penetration beyond the outer longitudinal muscle layer was measured according to a 5-mm cut-off point. Concordance rate and Kappa coefficient were calculated for both techniques. Primary end-points were disease free survival and overall survival (OS) for both groups. A total of 97 patients were included. Disease-free survival in depth of mesorectal invasion ≤5 and >5 mm measured by ERUS was 130.80 (119.20-142.30) vs. 88.38 (56.13-120.64) months (P=0.020), respectively, and 129.90 (117.90-141.90) vs. 93.60 (64.50-122.70) months (P=0.045) when measured by magnetic resonance imaging. Depth of mesorectal invasion ≤5 mm measured by ERUS and MRI was a prognostic factor for both OS [ERUS P=0.009; MRI P=0.019] and DFS (ERUS P=0.026; MRI P=0.054) after Cox regression analysis. T3 subclassification above and below 5mm is feasible by ERUS, shows good concordance with validated magnetic resonance and can easily be incorporated into the diagnostic workup for these patients with possible survival implications.

NEUROMUSCULAR AND VASCULAR HAMARTOMA SECONDARY TO ENDOMETRIOSIS AT APPENDICEAL TIP MISDIAGNOSED AS APPENDICEAL NEOPLASM: AN EXTREMELY RARE CASE REPORT WITH LITERATURE REVIEW

Background: Endometriosis of the appendix is reported to be 1 to 3 % of the total endometriosis. Neuromuscular and vascular hamartoma (NMVH) is a rare lesion with only 27 cases reported in intestine since its initial description in 1982 and only one reported case in the appendix until now. We present a 52-year-old Omani female patient complaining of chronic interm Case presentation: itted abdominal pain. On CT scan (computed tomography scan), there was appendiceal lesion near the tip suggestive of mucinous cystadenoma. Diagnostic laparoscopy with appendectomy was conducted. There was a well-dened lesion with central fatty area at appendiceal tip focally merge with the outer muscle layer and mostly embedded in the mesoappendix. Microscopic examination showed focal area of endometriosis at the outer longitudinal muscle layer of the appendix. This focally merge with a well-dened mass like lesion that is embedded in the mesoappendix. The lesion composed of benign random arranged smooth muscle bers, scattered nerve bundles, some of which showed ganglionic cells including degenerated one, adipose tissue, thin and thick-walled small blood vessels. Features were consistent with NMVH that appeared secondary to the nearby endometriosis. Conclusion: Endometriosis of bowel should be suspected in female with longstanding intermitted abdominal pain. NMVH is extremely rare in appendix, thus clinical and radiological suggestion of such diagnosis is difcult. Secondary neuromuscular hamartoma is reported in association with Crohn's disease as a consequence of the chronic inammation and thus could be suspected secondary to endometriosis

Histomorphometric analysis of mature female Japanese quail (Coturnix coturnix japonica) stomach

The study analyzed the histomorphometry of the mature female Japanese quail (Coturnix coturnix japonica) stomach with the aid of ImageJ software. The different histological parts were identified using a compound microscope. Five mature laying female Japanese quail were collected and necropsied. The digestive organs, particularly proventriculus and gizzard, were collected and processed for tissue staining. Histological identification and measurement of thickness and depth of various structures were subsequently performed. Comparable to other avian species, the proventriculus was comprised of four layers: thin tunica serosa (22.69 µm), tunica muscularis (235.07 µm) with outer longitudinal and inner circular smooth muscle layers, thick tunica submucosa (2,164.37 µm) containing glands, and innermost tunica mucosa (553.42 µm) with papillae. The gizzard was characterized by four tunics: thin tunica serosa (60.44 µm), thick tunica muscularis (1,480.07 µm), tunica submucosa (112.25 µm), and tunica mucosa (456.15 µm) where the glands, crypts, and koilin can be found. The findings suggest that the histology of proventriculus and gizzard of the Japanese quail have no remarkable difference compared to other poultry species. However, the histomorphometry of the organs examined had remarkable variations as compared to other avians.

Gross Anatomy and Histological Features of Gymnarchus niloticus (Cuvier, 1829) from the River Niger at Agenebode in Edo State, Nigeria

This study was conducted to record the anatomy and histological features of the gastrointestinal tract of the trunk fish Gymnarchus niloticus captured at Agenebode in the Lower River Niger, Edo State. The gastrointestinal tract was segmented into the mouth, oesophagus, stomach, pyloric caeca, and intestine. The slender (taeniform) body that is fuller at the head tappers at its end. There are no spines on this fish, and the fins used for locomotion are the dorsal fins and not the typical pectoral fins as in other fish. The oesophagus, stomach, pyloric caeca, intestine, and cloaca (anterior, intermediate, posterior, and rectum) were analysed for histological examination. The stomach had significantly higher villi and thicker inner circular muscles compared to the intestine and oesophagus. The lamina propria was thickest in the stomach which is significantly higher when compared with the oesophagus, but not with the intestine. However, the intestine showed significantly thicker outer longitudinal muscle, while gastric glands were observed only in the stomach. The histological features were closely associated with the functions of the different segments of the gastrointestinal tract. In conclusion, the histological features of the gastrointestinal tract of G. niloticus are consistent with the feeding habit of a carnivorous fish. In conclusion, the GIT is a complex structure composed of organs that reveals that it is a higher vertebrate created for a hardy survival, consistent with the feeding habit of a carnivorous fish. The histology reveals a GIT formed by four conspicuous layers from the inside to the outside of the mucosa, submucosa, and an inner longitudinal layer of the muscularis and the outer circular of the muscularis typical of higher vertebrates.

Fatal multiple intestinal intussusceptions and torsion secondary to a non-degradable foreign body gastrointestinal obstruction in a captive Lion (Panthera leo)

Intussusception is the invagination of one segment of the intestine into the part of the tract that either precedes or follows in the gastrointestinal tract of different species of animals. This report describes a case of fatal multiple intestinal intussusceptions and torsion associated with non-degradable foreign body gastrointestinal obstruction in a captive lion (Panthera leo) in a zoo in Nigeria. Parenchymatous tissues were aseptically collected during necropsy for bacteriological isolation and histopathology. Also, intestinal fecal material was collected and sent for parasitological examination. The main lesions were gastroduodenal, duodeduodenal, duodejejunal and jejunojenunal intussusceptions and duodenal torsion. A non-degradable towel-like fabric foreign body obstruction along the pyloric antrum/canal region of the stomach down to the jejunum was found. Microscopic lesion included ischemic necrosis of inner circular and outer longitudinal smooth muscles of the intestine with necrosis of other layers and vascular congestion. Parasitological examination revealed presence of Babesia spp. in blood smear examined before the death of the lion. While Escherichia coli was isolated from the liver on MacConkey agar. A diagnosis of intussusception and torsion associated with non-degradable foreign body (fabric) gastrointestinal obstruction was made. This first case of ingestion of a non-degradable fabric foreign body leading to gastrointestinal obstruction in captive lion in Nigeria has brought about the need for vigilance of zoo authority to prevent a recurrence during crowd influx to the garden.

Redescription of Cerebratulus marginatus auct. (Nemertea: Pilidiophora) from Hokkaido, Japan, as a new species.

The heteronemertean Cerebratulus orochi sp. nov. is described based on material collected intertidally at a muddy beach in Akkeshi, northern Japan. For the last 80 years, the species has been confused with Cerebratulus marginatus Renier, 1804; the latter was originally described from the Adriatic and once believed to occur in many places in the northern hemisphere including Japan. Cerebratulus orochi sp. nov. is morphologically different from all the congeners including C. marginatus by the following combination of characters: several layers of diagonal-muscle meshwork coated with connective tissue, proximo-distally distributed in cross section from the distal portion of the body-wall outer longitudinal muscle layer to the cutis-gland zone throughout the anterior portion of the body from the precerebral to the foregut regions; the cephalic vascular system consisting of lateral and mid-dorsal vessels; and the sub-rhynchocoelic vessel possessing a pair of antero-lateral diverticula before the former forks posteriorly into a pair of lower lateral vessels in the post-cerebral, pre-oral region. Previous records of C. marginatus from Japanese waters are no longer considered to be substantiated. Multi-locus phylogenetic analyses based on the mitochondrial 16S rRNA and cytochrome c oxidase subunit I (COI), as well as the nuclear 18S rRNA, 28S rRNA, and histone H3 genes among heteronemerteans comprising the "Cerebratulus clade" indicated that C. orochi sp. nov. was closely related to C. cf. marginatus from the US Pacific coast. A MegaBLAST search at the NCBI website with the 16S rRNA gene sequence from C. orochi sp. nov. followed by a couple of species delimitation analyses suggests that larvae of the species are also distributed in Vostok Bay, Far East Russia.

A novel third mesh-like myometrial layer connects the longitudinal and circular muscle fibers -A potential stratum to coordinate uterine contractions-

Periodic myometrial contraction is one of the important uterine functions to achieve embryo implantation and parturition. Although it is well-known that the mammalian myometrium is composed of longitudinal (outer) and circular (inner) layers, the precise mechanisms that coordinate both muscular contractions to produce peristaltic movements remain unclear. Recently, by treatment with our modified Clear Unobstructed Brain Imaging Cocktails and Computational analysis (CUBIC) tissue-clearing method, we obtained well-contrasted three-dimensional images of the transparent murine ovary using enhanced green fluorescent protein (EGFP) transgenic mice and light-sheet microscopy. Consequently, to investigate accurate anatomical connections between outer and inner myometrial fibers, we observed whole structures of the myometrium using a transparent murine uterus. By this method, we identified a novel muscle layer, a middle layer of the myometrium, which anatomically connects the conventional outer longitudinal and inner circular muscles. This new layer was visualized as a mesh-like structure and this structure was observed throughout the whole uterus from proximal to distal sites. In this area, CD31-positive vessels were abundantly localized around the mesh-like muscle fibers. In addition, CD34-positive uterine telocytes and tubulin β-3-positive nerve fibers were closely located in this middle layer. These findings indicate the presence of a novel mesh-like stratum that connects longitudinal and circular muscle layers, and suggest its coordinating role in myometrial contractions.